U.S. Pat. No. 5,182,770 to Medveczky, et al., describes an integrated software piracy prevention system incorporating several characteristic identification codes identifying installation and software components. A separate security device is attached to and in communication with the protected computer system. It is interactively queried regarding proper authorization of the current user. This approach provides economical tracking of licensees and their use of sophisticated programs.
U.S. Pat. No. 5,857,025 to Anderson, et al., describes using a device and method using a split processor based architecture to provide physical security of critical information by implementing a required protocol before releasing critical information. The critical information is used as a key to a cryptographic algorithm. A chaotic cryptographic algorithm is also provided including a defined key space employing six parameters of a Lorenzian system of equations.
U.S. Pat. No. 6,088,450 to Davis, et al., describes a wireless authentication system to control an operating state of a node being a computer, door control mechanism or any multi-state product based on the proximity of an authorized user to the node. The wireless authentication system comprises a security device implemented within the computer and a user authentication token (“token”) in possession of the authorized user. A Challenge/Response protocol is configured between the security device and the token. The first successful Challenge/Response message exchange between the security device and the token places the node in an operational state allowing the authorized user access to the contents and/or networked resources of the node. Later Challenge/Response message exchanges are set to occur periodically to check whether the authorized user possessing the token has left the node unattended thereby causing the node to be placed in a non-operational state.
The FROG block cipher (see tecapro.com/aesfrog.html) is a block cipher which hides the exact sequence of primitive operations even though the cipher itself is known. When other ciphers use the secret key only as data (which are combined with the plaintext to produce the ciphertext) FROG uses the key both as data and as instructions on how to combine these data. In effect an expanded version of the key is used by FROG as a program. FROG itself operates as an interpreter that applies this key-dependent program on the plaintext to produce the ciphertext.
The disclosures of all references mentioned above and throughout the present specification, as well as the disclosures of all references mentioned in those references, are hereby incorporated herein by reference.